When an emergency or processing of an emergent affair occurs, a congestion of network resources may be caused. However, to ensure the work of people such as government officials, firemen and policemen using the normally used network resources, these people may be given the priority to use the network resources that these people can still access the network and acquire services during a network congestion. The service that a specific user has the priority to access the network is called eMPS.
An EPS (Evolved Packet System, an evolved packet system) is a new mobile communication network defined under the guidance of an evolved plan. Although the EPS has a new network framework, a lot of voice services of an operator run in a CS (Circuit Switched, circuit switched) domain of an original 2G or 3G network. To reuse the existing CS domain in the EPS, the industry provides a technology of connecting a CS domain core network to an EPS network through an MSC (Mobile Switch Center, mobile switch center) entity in a 2G or 3G network and falling back to the CS domain through the connection to execute the voice service. The technology is called CSFB. The main execution process of CSFB includes:
When a UE (User Equipment, user equipment) prepares to initiate a CS mobile originating (Mobile Originating, MO) service, the UE needs to switch to the 2G or 3G network preferentially and choose to camp on one 2G or 3G cell, and then starts the MO service; when the MSC entity receives one mobile terminated (MT, Mobile Terminated) service, through a SGs interface between the MSC entity and an MME (Mobility Management Entity, mobility management entity), the MSC entity sends an MT paging message to the MME, and the MME pages the UE through an EPS network; after receiving the MT paging message, the UE first needs to switch to the 2G or 3G network preferentially and choose to camp on one 2G or 3G cell, and then completes subsequent processing of the MT service.
If a network side fails to learn whether a UE has a priority access right when the eMPS needs to be performed in the CSFB mechanism, the network side fails to provide an eMPS service for the UE.